Test-retest reliability of physiotherapists using the action research arm test in chronic stroke

Purpose: The aim of this study was to determine whether physiotherapists (PT) scores are consistent over time when using Action Research Arm Test (ARAT) to assess upper limb (UL) function on a videotaped chronic stroke patient. Subjects and Methods: Quantitative correlational study. A convenience-snowball sample of 20 international PT (mean age and experience = 32 ± 6.8 and 7.55 ± 7.4 years) used ARAT to score chronic stroke patient’s UL function, observing a video at baseline and again ≈ 2 weeks later. Two sets of non-parametric ordinal data were assessed with Spearman’s (rho) and the alpha (a) value was set at 0.01. Line of equality, Bland-Altman plots and Wilcoxon signed rank test were also considered. Results: Spearman’s rho was found ≈ 0.78 at a significance level of 0.00. ARAT was scored with a mean difference of 16.6 days and a mean change of 0.6 points was observed. Limits of agreement and coefficient of reproducibility were ±2.3 and ±2.6 respectively. The patient’s arm impairment was categorised as moderate and floor or ceiling effects were not detected. Conclusion: The results suggest that ARAT is consistent, valid and should be used by PT in chronic stroke.<br/

The trapping of equatorial magnetosonic waves in the Earth’s outer plasmasphere

Abstract We investigate the excitation and propagation of equatorial magnetosonic waves observed by the Van Allen Probes and describe evidence for a trapping mechanism for magnetosonic waves in the Earth\u27s plasmasphere. Intense equatorial magnetosonic waves were observed inside the plasmasphere in association with a pronounced proton ring distribution, which provides free energy for wave excitation. Instability analysis along the inbound orbit demonstrates that broadband magnetosonic waves can be excited over a localized spatial region near the plasmapause. The waves can subsequently propagate into the inner plasmasphere and remain trapped over a limited radial extent, consistent with the predictions of near-perpendicular propagation. By performing a similar analysis on another observed magnetosonic wave event, we demonstrate that magnetosonic waves can also be trapped within local density structures. We suggest that perpendicular wave propagation is important for explaining the presence of magnetosonic waves in the Earth\u27s plasmasphere at locations away from the generation region. Key Points Magnetosonic waves are excited by ion ring distributions near the plasmapauseMagnetosonic waves are trapped in a limited radial region in the plasmasphereMagnetosonic waves are modulated by local density structures

Quality and location choices under price regulation

In a model of spatial competition, we analyze the equilibrium outcomes in markets where the product price is exogenous. Using an extended version of the Hotelling model, we assume that firms choose their locations and the quality of the product they supply. We derive the optimal price set by a welfarist regulator. If the regulator can commit to a price prior to the choice of locations, the optimal (second-best) price causes overinvestment in quality and an insufficient degree of horizontal differentiation (compared with the first-best solution) if the transportation cost of consumers is sufficiently high. Under partial commitment, where the regulator is not able to commit prior to location choices, the optimal price induces first-best quality, but horizontal differentiation is inefficiently high

Resonant scattering of energetic electrons by unusual low-frequency hiss

Abstract We quantify the resonant scattering effects of the unusual low-frequency dawnside plasmaspheric hiss observed on 30 September 2012 by the Van Allen Probes. In contrast to normal (∼100-2000 Hz) hiss emissions, this unusual hiss event contained most of its wave power at ∼20-200 Hz. Compared to the scattering by normal hiss, the unusual hiss scattering speeds up the loss of ∼50-200 keV electrons and produces more pronounced pancake distributions of ∼50-100 keV electrons. It is demonstrated that such unusual low-frequency hiss, even with a duration of a couple of hours, plays a particularly important role in the decay and loss process of energetic electrons, resulting in shorter electron lifetimes for ∼50-400 keV electrons than normal hiss, and should be carefully incorporated into global modeling of radiation belt electron dynamics during periods of intense injections

Analysis of plasmaspheric hiss wave amplitudes inferred from low-altitude POES electron data: Technique sensitivity analysis

A novel technique capable of inferring wave amplitudes from low-altitude electron measurements from the Polar Operational Environmental Satellites (POES) spacecraft has been previously proposed to construct a global dynamic model of chorus and plasmaspheric hiss waves. In this paper we focus on plasmaspheric hiss, which is an incoherent broadband emission that plays a dominant role in the loss of energetic electrons from the inner magnetosphere. We analyze the sensitivity of the POES technique to different inputs used to infer the hiss wave amplitudes during three conjunction events with the Van Allen Probes. These amplitudes are calculated with different input models of the plasma density, wave frequency spectrum, and electron energy spectrum, and the results are compared to the wave observations from the twin Van Allen Probes. Only one parameter is varied at a time in order to isolate its effect on the output, while the two other inputs are set to the values observed by the Van Allen Probes. The results show that the predicted hiss amplitudes are most sensitive to the adopted frequency spectrum, followed by the plasma density, but they are not very sensitive to the electron energy spectrum. Moreover, the standard Gaussian representation of the wave frequency spectrum (centered at 550 Hz) peaks at frequencies that are much higher than those observed in individual cases as well as in statistical wave distributions, which produces large overestimates of the hiss wave amplitude. For this reason, a realistic statistical model of the wave frequency spectrum should be used in the POES technique to infer the plasmaspheric hiss wave intensity rather than a standard Gaussian distribution, since the former better reproduces the observed plasmaspheric hiss wave amplitudes

Modeling inward diffusion and slow decay of energetic electrons in the Earth\u27s outer radiation belt

Abstract A new 3-D diffusion code is used to investigate the inward intrusion and slow decay of energetic radiation belt electrons (\u3e0.5 MeV) observed by the Van Allen Probes during a 10 day quiet period on March 2013. During the inward transport, the peak differential electron fluxes decreased by approximately an order of magnitude at various energies. Our 3-D radiation belt simulation including radial diffusion and pitch angle and energy diffusion by plasmaspheric hiss and electromagnetic ion cyclotron (EMIC) waves reproduces the essential features of the observed electron flux evolution. The decay time scales and the pitch angle distributions in our simulation are consistent with the Van Allen Probe observations over multiple energy channels. Our study suggests that the quiet time energetic electron dynamics are effectively controlled by inward radial diffusion and pitch angle scattering due to a combination of plasmaspheric hiss and EMIC waves in the Earth\u27s radiation belts

Radiation belt electron acceleration by chorus waves during the 17 March 2013 storm

Abstract Local acceleration driven by whistler-mode chorus waves is fundamentally important for accelerating seed electron populations to highly relativistic energies in the outer radiation belt. In this study, we quantitatively evaluate chorus-driven electron acceleration during the 17 March 2013 storm, when the Van Allen Probes observed very rapid electron acceleration up to several MeV within ~12 hours. A clear radial peak in electron phase space density (PSD) observed near L* ~4 indicates that an internal local acceleration process was operating. We construct the global distribution of chorus wave intensity from the low-altitude electron measurements made by multiple Polar Orbiting Environmental Satellites (POES) satellites over a broad region, which is ultimately used to simulate the radiation belt electron dynamics driven by chorus waves. Our simulation results show remarkable agreement in magnitude, timing, energy dependence, and pitch angle distribution with the observed electron PSD near its peak location. However, radial diffusion and other loss processes may be required to explain the differences between the observation and simulation at other locations away from the PSD peak. Our simulation results, together with previous studies, suggest that local acceleration by chorus waves is a robust and ubiquitous process and plays a critical role in accelerating injected seed electrons with convective energies (~100 keV) to highly relativistic energies (several MeV)